Tag: physics

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Questions Related to physics

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

If a body is moving with a constant speed along a straight line; then in order to change its direction of motion, an external force has to be applied in a direction normal to the direction of motion.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Newton's First law of motion - "Every body continues to be in its state of rest or of uniform motion in a straight line unless compelled by some external force to act otherwise". 

According to Newton's First law of motion, statement is true, an external force has to be applied in a direction normal to the direction of motion to change its direction of motion

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

Three forces are acting on a body in which of following option (s) can the body be in equilibrium?

  1. $2N, 4N, 5N$
  2. $1N, 2N, 4N$
  3. $3N, 3N, 7N$
  4. $5N, 2N, 1N$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Three force are in equilibrium if 

1) All forces are in a plane 
2) Sum of two small forces is less than bigger force.
This condition is satisfy by option A
Answerer A

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

 A force of $15 N$ increases the length ofa by $1 \mathrm { mm }$. The additional force require increase the length by $2.5 \mathrm { mm }$ in N is 

  1. $2.25$
  2. $22.5$
  3. $37.5$
  4. $3.75$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

We know,

$Y=\dfrac{FL}{A\Delta L}$

For a wire, A,L,Y are constant.

$\dfrac{F}{\Delta L}=$constant

Let extra Force needed be $ F$,

$\dfrac{15}{1}=\dfrac{F+15}{2.5}$

$F+15=2.5\times 15$

$F=1.5\times 15=22.5$

Option $\textbf B$ is the correct answer
Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

A lift coming down is just about to reach the ground floor. Taking the ground floor as origin and positive direction upwards for all quantities, which of the following is correct ($x$=displacement, $v$= velocity, $a$=acceleration):

  1. $x < o, v<0, a>0$
  2. $x > 0, v < 0, a < 0$
  3. $x > 0, v < 0, a> 0$
  4. $x > 0, v >0,a >0$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If the lift is below the origin (ground floor), x < 0. If it is moving down, v < 0. If it is slowing down to reach the ground, it must have an upward acceleration, so a > 0.

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

A particle moves in a potential region given by $U = 8{x^2} - 4x + 400\,J.$ Its state of equilibrium will be$-$ 

  1. 8 m

  2. 10 m

  3. 12 m

  4. 0.25 m
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$U = 8x^2 - 4x + 400$
Differentiate with $dx$ we will get $F$
$F = 16x - 4$
At equilibrium $F = 0$
$0 = 16x - 4$
$x = 1/4 = 0.25 m$
It’s state of equilibrium will be at $x = 0.25 m$

Hence,
option $(D)$ is correct answer.

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

A force produces transnational motion:

  1. when the body is free to move

  2. when the body is hindered to move

  3. when the body is rigidly fixed

  4. when none of the above are true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the application of translational motion the body must be free to move and after applying force, all the particles in that body move with same velocity.